Anatomic fit of a percutaneous VAD for right heart support

ABSTRACT

An apparatus is disclosed including: a cannula having a shape closely matched to the anatomy of the right ventricle of the human heart, where the cannula has an outflow port configured to be located proximal the pulmonary artery and an inflow port located proximal the inferior vena cava. In some embodiments, the cannula is a close fit to the anatomy of at least 90%, 95%, or more of the population.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is the U.S. National Stage of PCT InternationalApplication Number PCT/US2011/037984, filed May 25, 2011, which claimsbenefit of U.S. Provisional Patent Application Ser. No. 61/396,344 filedMay 26, 2010. The entire contents of the foregoing applications arehereby incorporated herein by reference in their entireties.

BACKGROUND

The present disclosure relates generally to the field of ventricularassist devices. A ventricular assist device, or VAD, is a mechanicalcirculatory device that is used to partially or completely replace thefunction of a failing heart. Some VADs are intended for short term use,typically for patients recovering from heart attacks or heart surgery,while others are intended for long term use (months to years and in somecases for life), typically for patients suffering from congestive heartfailure.

VADs are designed to assist either the right (RVAD) or left (LVAD)ventricle, or both at once (BiVAD). Which of these types is used dependsprimarily on the underlying heart disease and the pulmonary arterialresistance that determines the load on the right ventricle. In someapplications a percutaneous RVAD to support the right heart must pumpblood across the pulmonary valve.

SUMMARY

The inventors have realized that a cannula may be provided which closelymatches the anatomy of the vast majority of patients and is suitable foruse in a VAD device, e.g., an RVAD. Medical images (e.g., CT scans) ofthe hearts of one or more subjects may be analyzed, e.g., to determinethe position of one or more anatomical landmarks. This analysis may beused to generate a cannula shape design (e.g., of the type describedherein) that matches the anatomy of most patients.

In a first aspect, an apparatus is disclosed including: a cannula havinga shape closely matched to the anatomy of the right ventricle of thehuman heart. In some embodiments, the cannula has an outflow portconfigured to be located proximal the pulmonary artery (PA) and aninflow port located proximal the inferior vena cava (IVC). In someembodiments, the cannula is configured to traverse the right atrium(RA), tricuspid valve (TV) and pulmonic valve (PV).

In some embodiments, the cannula includes: a primary sectioncorresponding to the path from the diaphragm fibrous ring in the IVC tothe IVC to RA transition (IVC-RA); a secondary section corresponding tothe path from the IVC-RA to the TV; a tertiary section corresponding tothe path from the TV to the PV; and a quaternary section correspondingto the path between the PV and the left branch of the pulmonary artery.In some embodiments, the primary section extends to the inflow port andthe inflow port is configured to be located beyond the diaphragm fibrousring of the IVC.

In some embodiments, the cannula includes: a first segment extendingfrom a point A to a point B having the inflow port proximal point A; asecond segment extending from a point B to a point C; a third segmentextending from a point C to a point D; and a fourth segment extendingfrom a point D to a point E, having the outflow port proximal point E.In some embodiments, the first, second and third segments liesubstantially in a first plane containing points A, B, and C. In someembodiments, the forth segment lies substantially in a second planecontaining points C, D, and E, the second plane being oriented to thefirst plane at an angle of about 30 degrees. In some embodiments, thefirst segment has a length of about 28 mm. In some embodiments, thesecond segment has a length of about 44 mm. In some embodiments, thethird segment has a length of about 48 mm. In some embodiments, thefourth segment has a length of about 56 mm. In some embodiments, thesecond segment is oriented to the first segment at an angle of about 63degrees in the first plane, with a bend radius of curvature of about 25mm.

In some embodiments, the third segment is oriented to the first segmentat an angle of about −30 in the first plane, with a bend radius ofcurvature of about 45 mm. In some embodiments, the forth segment isoriented to the third segment at an angle of about −87 degrees in thesecond plane, with a bend radius of curvature of about 25 mm.

Some embodiments include a pigtail extension extending from the end ofthe fourth segment at a point proximal point E, the pigtail extensionlying substantially in a third plan oriented at an angle of about −30degrees to the second plane.

In some embodiments, the cannula is formed of a biocompatible material.

In some embodiments, the cannula is formed of a substantially rigidmaterial.

In some embodiments, the cannula is formed of an at least partiallyflexible material.

In some embodiments, the cannula includes a polyurethane tube reinforcedwith a surrounding coil of nitinol

Some embodiments include a percutaneous ventricular assist deviceincluding the cannula, and including at least on pump located within thecannula.

In some embodiments, the cannula has a shape closely matched to theanatomy of at least 80% of the adult human population, at least 90% ofthe adult human population at least 95% of the adult human population,or more.

In another aspect, a method is disclosed including forming a cannula ofthe type recited above.

In another aspect, a method is disclosed including implanting anapparatus as recited above in a human heart.

In another aspect, a method including: receiving medical image datacorresponding the anatomy of the right ventricle of each of a pluralityof human subjects; processing the medical image data to determinelandmark information indicative of the position of a plurality ofanatomical landmarks; and generating a cannula design based on thelandmark information. Some embodiments include fabricating a cannulabased on the cannula design.

In some embodiments, processing the medical image data to determinelandmark information includes: for each of the plurality of humansubjects, generating information indicative of a position of the IVC,RA, TV, PV and PA.

In some embodiments, the information indicative of the position of theIVC, RA, TV, PV and PA includes: a length and an angle between the IVCand the RA; a length and an angle between the RA and the TV; a lengthand an angle between the TV and PV; and a length and an angle betweenthe PV and PA.

Some embodiments include: fabricating the cannula includes fabricatingthe cannula having a shape closely matched to the anatomy of the rightventricle of the human heart, where the cannula has an outflow portconfigured to be located proximal the PA and an inflow port locatedproximal the IVC.

In some embodiments, the cannula is configured to traverse the rightatrium (RA), tricuspid valve (TV) and pulmonic valve (PV).

In some embodiments, the cannula includes: a primary sectioncorresponding to the path from the diaphragm fibrous ring in the IVC tothe IVC to RA transition (IVC-RA); a secondary section corresponding tothe path from the IVC-RA to the TV; a tertiary section corresponding tothe path from the TV to the PV; and a quaternary section correspondingto the path between the PV and the left branch of the pulmonary artery.

In some embodiments, the cannula has a shape closely matched to theanatomy of at least 80%, 85%, 90%, 95% or more of the adult humanpopulation.

In another aspect, a product is disclosed including: a cannulafabricated using any method recited above.

Each of the aspects and embodiments of the invention described hereincan be used alone or in combination with one another.

The aspects and embodiments will now be described with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows percutaneous VAD located in the right ventricle of a heart.

FIGS. 2A-2E each show a different perspective views of a cannula havinga shape closely matched to the anatomy of the right ventricle in a broadrange of subjects. For each figure, a Cartesian coordinate (x,y,z) keyindicates the viewing direction.

FIG. 3 is a table showing a summary of design parameters for a cannula.

FIG. 4 illustrates a process for designing a cannula.

FIG. 5 illustrates the results of a right ventricle cannula fit studywhich determined the location of anatomical landmarks.

FIG. 6 is a plot of a characteristic length between anatomical landmarksin each of multiple subjects as a function the respective subject bodysurface area.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a catheter-based percutaneous VAD 100 for treatmentof acute right heart failure is shown. As shown, the device inflow 101resides in the inferior vena cava (IVC); a flexible cannula 105traverses the right atrium (RA), tricuspid (TV) and pulmonic valves(PV), while the device outflow 102 resides in the pulmonary artery (PA).The cannula may house a drive system and pump, e.g., of the types usedin VADs available under the Impella trade name from Abiomed, Inc ofDanvers, Mass. In some embodiments, the device provides flows of up to 4L/min or more and up to 2 weeks of support or more.

The shape of cannula 105 closely matches the anatomy of the rightventricle of the human heart. For example, as described in greaterdetail below, the shape of the cannula may be based on a fit study of apopulation of subjects, e.g., using a library of medical images (e.g.,CT or MRI scan images) of the subjects. In some embodiments, the cannulais a close fit to the anatomy of at least 80%, 85%, 90%, 95%, or more ofa population (e.g., the adult human population, adult male humanpopulation, adult female human population, the human population for agiven age range, etc.).

FIGS. 2A-2E show several perspective views of an embodiment of the RVADcannula 105. As shown in FIG. 2A, the cannula extends between the inflowport 101 and the outflow port 102 and includes primary, secondary,tertiary, and quaternary sections labeled 1, 2, 3, and 4, respectively.

Beginning at the inflow port 101, the cannula 105 includes asubstantially straight 28 mm primary section 1 extending between pointsA and B. The cannula 105 next includes a secondary section 2 extendingfrom point B to point C. The secondary section 2 has a length of 44 mm.The angle formed between the primary and secondary sections 1, 2 is 63degrees, with a radius of curvature of 25 mm. (See FIG. 2B.)

The secondary section 2 is followed by a tertiary section 3 extendingfrom point C to point D. The tertiary section has a length of 48 mm. Theangle formed between the secondary and tertiary sections is −30 degrees,with a radius of curvature of 45 mm. (See FIG. 2C.) The tertiary section3 is followed by a quaternary section 4 extending from point D to pointE. The quaternary section has a length of 56 mm. The angle formedbetween the tertiary and quaternary sections in the plane defined bypoints C-D-E is −87 degrees, with a radius of curvature of 25 mm. (SeeFIG. 2C.)

Note that the point E lies outside of the plane defined by points A-B-C.As shown in FIG. 2D, the plane defined by points A-B-C is oriented at anangle of 33 degrees to the plane define by points C-D-E.

In some embodiments, contiguous to the input port 101 of the cannula 105is an extension 107 (e.g. of soft elastic material) that mechanically,yet not hydraulically extends the cannula 13. In some embodiments, thisextension 107 is provided with a pigtail tip 109 to allow for atraumatic support on body tissue. As shown in FIG. 2E, the pigtail tip109 may be oriented at an angle of e.g., −30 degrees from the planedefined by points C-D-E.

FIG. 3 is a table summarizing the above-described dimensions of anembodiment of the RVAD cannula shown in FIGS. 2A-2E. In variousembodiments, the length, radius and/or angle dimensions may vary fromthe values given below by less that 0.1%, 1%, 2%, 3%, 4%, 5%, 10% etc.

In various embodiments, the cannula 105 has an inner diameter in therange of 5-10 mm, e.g., 6 mm and an outer diameter of 5-10 mm, e.g., 7mm. In some embodiments, other suitable dimensions may be used. Thecannula may be constructed of any suitable biocompatible material. Thematerial may be substantially rigid or at least partially flexible. Inone embodiment, the cannula is constructed of a polyurethane tubereinforced with a coil of nitinol (or other suitable material, e.g., amaterial featuring shape memory). In some embodiments, the polyurethanematerial may include the material having the trade name Desmopan 355,available from Bayer MaterialScience AG of Leverkusen, Germany.

The cannula 105 may be fabricated using any techniques know in the artincluding, e.g., molding, injection molding, etc.

As noted above, the cannula 105 is designed to closely match the anatomyof the right ventricle. In some embodiments, each section of the cannulais designed to extend between the expected locations of variousanatomical landmarks (e.g., as determined based on the average locationof these landmarks found using an anatomical fit study). For example, inthe embodiments described above, the primary section 1 corresponds tothe path from the diaphragm fibrous ring in the IVC to the IVC to RAtransition (IVC-RA). The secondary section 2 corresponds to the pathfrom the IVC-RA to the TV. The tertiary section 3 corresponds to thepath from the TV to the PV. The quaternary section 4 corresponds to thepath between the PV and the left branch of the PA. As shown, the lengthof the primary section 1 is chosen such that the inflow port 101 islocated beyond the diaphragm fibrous ring. As shown, the length of thequaternary section 4 is chosen such that the outflow port 102 is locatedat the left PA bifurcation, with extension 107 residing in the left PA.

It is to be understood that, in other embodiments, any other suitablechoice of landmarks may be used. To ensure a cannula shape whichconforms to the anatomy of a wide range of patients, it is advantageousto select a set of landmarks having relative locations which exhibit lowpatient-to-patient variability do not depend strongly on the size of thepatient (e.g., as determined by the patients body surface area (BSA)).As discussed in greater detail below, the landmarks described above meetboth of these criteria.

In various embodiments, the RVAD device 100 includes the cannula 105described above enclosing one or more pumps and pump motor drives (notshown). Any suitable pump and/or drive known in the art may be used. Insome embodiments, the cannula may be a component of a BiVAD device.

In some embodiments the RVAD is advantageously small, with a lowblood-wetted surface area, e.g., of 100 cm² or less, 75 cm² or less, 50cm² or less, 25 cm² or less, 10 cm² or less, etc. (e.g., in the range of10-100 cm²).

In some embodiments the cannula may be introduced into the ventricleusing a catheter based technique, e.g., of the types described inCannula Systems and Methods of Use, U.S. Pat. Pub. No. 20070066943 filedMar. 22, 2007, the entire contents of which is incorporated herein byreference.

FIG. 4 illustrates a process 400 for designing and producing a cannulaof the type described herein. In step 401, medical image data (e.g.,including 3D CT or MRI scans of the hearts of a set of patients) isreceived or obtained (e.g., from a database).

In step 402, a set of anatomical landmarks is selected (e.g., thelandmarks described with reference to FIGS. 2A-2E above). To ensure acannula shape which conforms to the anatomy of a wide range of patients,it is advantageous to select a set of landmarks having relativelocations which exhibit low patient-to-patient variability do not dependstrongly on the size of the patient (e.g., as determined by the patientsbody surface area (BSA)).

In step 403, the image data is analyzed to locate the anatomicallandmarks and determine information about their relative (and/orabsolute) positions. The landmarks may be identified automatically(using any image processing or machine vision techniques known in theart), manually (e.g., by presenting the images to a medical practitionerfor examination), or combinations thereof. Average positions for thelandmarks may be determined over a sample population of patients

In step 404, a cannula design is generated based on the analysisperformed in step 404. For example, the size and/or orientations ofvarious sections of the cannula may be determined based on the averagepositions for the landmarks over a sample population of patients, inorder to provide a cannula design which closely matches the anatomy ofthe heart over a large range of patients. The cannula design may beoutput (e.g., as a data file containing a listing a parameters, acomputer aided design (CAD) file, etc.).

In step 405, the cannula is produced based on the cannula designgenerated in step 404. As described above, the cannula may be fabricatedusing any suitable technique know in the art.

Example RVAD Cannula Design

The following sets for one non-limiting example of a cannula design.

Nineteen representative 3D CT scans of the hearts of patients having BSAranging from 1.5-2.6 m² were used to optimize cannula geometry using thetechniques described herein. Lengths and angles between the IVC, RA, TV,PV and PA were measured using Mimics software (available fromMaterialise NV, Belgium).

The results of the study are summarized in FIG. 5. Standard deviationsfor the length and angles were 6.3 mm and 11.4 degrees, showing lowpatient-to-patient variability. Further, as shown in FIG. 6, nocorrelation with BSA (body surface area) was found. Considerations weremade for the out-of-plane nature of the TV, while placement of thedevice outflow at the L bifurcation of the PA resulted in a 3D cannulaconfiguration, as described in detail above with reference to FIGS.2A-2E and FIG. 3.

The optimized cannula design was found to fit in 95% or more of patientsassuming a rigid cannula, and would fit as much as 100% of patientsallowing for cannula flexibility. Additional cadaver fit studies wereperformed which validated the computational modeling.

Although several specific example have been shown of devices for used inthe right ventricle in an adult human heart, it is to be understood thatthe devices and techniques described herein may be extended to otheranatomical locales (e.g. the left ventricle) and/or to other types ofsubjects, e.g., non-human animal subjects.

While various inventive embodiments have been described and illustratedherein, those of ordinary skill in the art will readily envision avariety of other means and/or structures for performing the functionand/or obtaining the results and/or one or more of the advantagesdescribed herein, and each of such variations and/or modifications isdeemed to be within the scope of the inventive embodiments describedherein. More generally, those skilled in the art will readily appreciatethat all parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the inventive teachingsis/are used. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific inventive embodiments described herein. It is,therefore, to be understood that the foregoing embodiments are presentedby way of example only and that, within the scope of the appended claimsand equivalents thereto, inventive embodiments may be practicedotherwise than as specifically described and claimed.

Inventive embodiments of the present disclosure are directed to eachindividual feature, system, article, material, kit, and/or methoddescribed herein. In addition, any combination of two or more suchfeatures, systems, articles, materials, kits, and/or methods, if suchfeatures, systems, articles, materials, kits, and/or methods are notmutually inconsistent, is included within the inventive scope of thepresent disclosure.

The above-described embodiments can be implemented in any of numerousways. For example, the embodiments may be implemented using hardware,software or a combination thereof. When implemented in software, thesoftware code can be executed on any suitable processor or collection ofprocessors, whether provided in a single computer or distributed amongmultiple computers.

Further, it should be appreciated that a computer may be embodied in anyof a number of forms, such as a rack-mounted computer, a desktopcomputer, a laptop computer, or a tablet computer. Additionally, acomputer may be embedded in a device not generally regarded as acomputer but with suitable processing capabilities, including a PersonalDigital Assistant (PDA), a smart phone or any other suitable portable orfixed electronic device.

Also, a computer may have one or more input and output devices. Thesedevices can be used, among other things, to present a user interface.Examples of output devices that can be used to provide a user interfaceinclude printers or display screens for visual presentation of outputand speakers or other sound generating devices for audible presentationof output. Examples of input devices that can be used for a userinterface include keyboards, and pointing devices, such as mice, touchpads, and digitizing tablets. As another example, a computer may receiveinput information through speech recognition or in other audible format.

Such computers may be interconnected by one or more networks in anysuitable form, including a local area network or a wide area network,such as an enterprise network, and intelligent network (IN) or theInternet. Such networks may be based on any suitable technology and mayoperate according to any suitable protocol and may include wirelessnetworks, wired networks or fiber optic networks.

A computer employed to implement at least a portion of the functionalitydescribed herein may comprise a memory, one or more processing units(also referred to herein simply as “processors”), one or morecommunication interfaces, one or more display units, and one or moreuser input devices. The memory may comprise any computer-readable media,and may store computer instructions (also referred to herein as“processor-executable instructions”) for implementing the variousfunctionalities described herein. The processing unit(s) may be used toexecute the instructions. The communication interface(s) may be coupledto a wired or wireless network, bus, or other communication means andmay therefore allow the computer to transmit communications to and/orreceive communications from other devices. The display unit(s) may beprovided, for example, to allow a user to view various information inconnection with execution of the instructions. The user input device(s)may be provided, for example, to allow the user to make manualadjustments, make selections, enter data or various other information,and/or interact in any of a variety of manners with the processor duringexecution of the instructions.

The various methods or processes outlined herein may be coded assoftware that is executable on one or more processors that employ anyone of a variety of operating systems or platforms. Additionally, suchsoftware may be written using any of a number of suitable programminglanguages and/or programming or scripting tools, and also may becompiled as executable machine language code or intermediate code thatis executed on a framework or virtual machine.

In this respect, various inventive concepts may be embodied as acomputer readable storage medium (or multiple computer readable storagemedia) (e.g., a computer memory, one or more floppy discs, compactdiscs, optical discs, magnetic tapes, flash memories, circuitconfigurations in Field Programmable Gate Arrays or other semiconductordevices, or other non-transitory medium or tangible computer storagemedium) encoded with one or more programs that, when executed on one ormore computers or other processors, perform methods that implement thevarious embodiments of the invention discussed above. The computerreadable medium or media can be transportable, such that the program orprograms stored thereon can be loaded onto one or more differentcomputers or other processors to implement various aspects of thepresent invention as discussed above.

The terms “program” or “software” are used herein in a generic sense torefer to any type of computer code or set of computer-executableinstructions that can be employed to program a computer or otherprocessor to implement various aspects of embodiments as discussedabove. Additionally, it should be appreciated that according to oneaspect, one or more computer programs that when executed perform methodsof the present invention need not reside on a single computer orprocessor, but may be distributed in a modular fashion amongst a numberof different computers or processors to implement various aspects of thepresent invention.

Computer-executable instructions may be in many forms, such as programmodules, executed by one or more computers or other devices. Generally,program modules include routines, programs, objects, components, datastructures, etc. that perform particular tasks or implement particularabstract data types. Typically the functionality of the program modulesmay be combined or distributed as desired in various embodiments.

Also, data structures may be stored in computer-readable media in anysuitable form. For simplicity of illustration, data structures may beshown to have fields that are related through location in the datastructure. Such relationships may likewise be achieved by assigningstorage for the fields with locations in a computer-readable medium thatconvey relationship between the fields. However, any suitable mechanismmay be used to establish a relationship between information in fields ofa data structure, including through the use of pointers, tags or othermechanisms that establish relationship between data elements.

Also, various inventive concepts may be embodied as one or more methods,of which an example has been provided. The acts performed as part of themethod may be ordered in any suitable way. Accordingly, embodiments maybe constructed in which acts are performed in an order different thanillustrated, which may include performing some acts simultaneously, eventhough shown as sequential acts in illustrative embodiments.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, Section 2111.03.

The foregoing detailed description has described only a few of the manyforms that this invention can take. For this reason, this detaileddescription is intended by way of illustration, and not by way oflimitation.

What is claimed is:
 1. A ventricular assist device comprising: aflexible cannula configured for catheter based percutaneous delivery,the cannula composed of a material featuring shape memory configured toprovide the cannula with a shape closely matched to the anatomy of theright ventricle of the human heart, wherein the cannula comprises: aprimary section corresponding to the path from the diaphragm fibrousring in the inferior vena cava (IVC) to the IVC to right atrium (RA)transition (IVC-RA); a secondary section corresponding to the path fromthe IVC-RA to the tricuspid (TV); a tertiary section corresponding tothe path from the TV to the pulmonic valve (PV); and a quaternarysection corresponding to the path between the PV and the left branch ofthe pulmonary artery (PA), wherein the cannula has an outflow portconfigured to be located proximal the PA, the outflow port positioned inthe quaternary section, and an inflow port configured to reside in theIVC, the inflow port positioned in the primary section and configured tobe located beyond the diaphragm fibrous ring of the IVC a pump enclosedwithin the cannula; and an extension extending from the quaternarysection.
 2. The device of claim 1, wherein the cannula is configured totraverse the right atrium (RA), tricuspid valve (TV) and pulmonic valve(PV).
 3. The device of claim 1, wherein the cannula comprises: a firstsegment extending from a point A to a point B having the inflow portproximal point A; a second segment extending from a point B to a pointC; a third segment extending from a point C to a point D; and a fourthsegment extending from a point D to a point E, having the outflow portproximal point E; wherein: the first, second and third segments liesubstantially in a first plane containing points A, B, and C; the forthsegment lies substantially in a second plane containing points C, D, andE, the second plane being oriented to the first plane at an angle ofabout 30 degrees; the first segment has a length of about 28 mm; thesecond segment has a length of about 44 mm; the third segment has alength of about 48 mm; the fourth segment has a length of about 56 mm;the second segment is oriented to the first segment at an angle of about63 degrees in the first plane, with a bend radius of curvature of about25 mm; the third segment is oriented to the first segment at an angle ofabout −30 in the first plane, with a bend radius of curvature of about45 mm; the forth segment is oriented to the third segment at an angle ofabout −87 degrees in the second plane, with a bend radius of curvatureof about 25 mm.
 4. The device of claim 3, wherein the extension includesa pigtail extension extending from the end of the fourth segment at apoint proximal point E, the pigtail extension lying substantially in athird plane oriented at an angle of about −30 degrees to the secondplane.
 5. The device of claim 3, wherein the cannula is formed of abiocompatible material.
 6. The device of claim 1, wherein the pump isconfigured for speed modulation of 50-250 ms/pulse.
 7. The device ofclaim 3, wherein the cannula is formed of an at least partially flexiblesubstantially rigid material.
 8. The device of claim 3, wherein thecannula comprises a polyurethane tube reinforced with a surrounding coilof nitinol.
 9. The device of claim 3, comprising a percutaneousventricular assist device comprising the cannula, and comprising atleast one pump located within the cannula.
 10. The device of claim 3,wherein the cannula has a shape closely matched to the anatomy of atleast 80% of the adult human population.
 11. The device of claim 3,wherein the cannula has a shape closely matched to the anatomy of atleast 90% of the adult human population.
 12. The device of claim 3,wherein the cannula has a shape closely matched to the anatomy of atleast 95% of the adult human population.
 13. A method comprising:forming a cannula as recited in claim
 5. 14. A method comprising:percutaneously implanting the device of claim 5 in a right ventricle ofa human heart such that the inflow port resides in the IVC and theextension is atraumatically supported on body tissue.
 15. A methodcomprising: receiving medical image data corresponding the anatomy ofthe right ventricle of each of a plurality of human subjects; processingthe medical image data to determine landmark information indicative ofthe position of a plurality of anatomical landmarks, the landmarksincluding the inferior vena cava (IVC), right atrium (RA), tricuspid(TV), pulmonic valve (PV) and pulmonary artery (PA); generatinginformation indicative of a position of the IVC, RA, TV, PV and PA; andgenerating a cannula design based on the landmark information, whereinthe cannula design includes: a primary section corresponding to the pathfrom the diaphragm fibrous ring in the IVC to the IVC to RA transition(IVC-RA), a secondary section corresponding to the path from the IVC-RAto the TV, a tertiary section corresponding to the path from the TV tothe PV, and a quaternary section corresponding to the path between thePV and the left branch of the PA, wherein the primary section of thecannula extends to the inflow port and the inflow port is configured tobe located beyond the diaphragm fibrous ring of the IVC, wherein thecannula has an outflow port configured to be located proximal the PA,wherein the outflow port is positioned in the quaternary section and aninflow port is located proximal the IVC, wherein the cannula includes apump enclosed within the cannula, and wherein the cannula includes anextension extending from the quaternary section fabricating a flexiblecannula configured for percutaneous delivery from a material featuringshape memory such that the shape memory material is configured toprovide the cannula with a shape based on the cannula design.
 16. Themethod of claim 15, wherein the information indicative of the positionof the IVC, RA, TV, PV and PA comprises: a length and an angle betweenthe IVC and the RA; a length and an angle between the RA and the TV; alength and an angle between the TV and PV; and a length and an anglebetween the PV and PA.
 17. The method of claim 16, wherein: fabricatingthe cannula comprises fabricating the cannula having a shape closelymatched to the anatomy of the right ventricle of the human heart,wherein the cannula has an outflow port configured to be locatedproximal the PA and an inflow port located proximal the IVC.
 18. Themethod of claim 17, wherein cannula is configured to traverse the rightatrium (RA), tricuspid valve (TV) and pulmonic valve (PV).
 19. Themethod of claim 18, wherein the cannula has a shape closely matched tothe anatomy of at least 90% of the adult human population.